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Figure F40. Thin section photomicrographs of altered olivine and plagioclase. A. Microphenocrysts of olivine completely altered to iddingsite and iron oxyhydroxides in a moderately olivine-phyric basalt clast (Sample 330-U1374A-9R-1, 24–28 cm; Thin Section 132; plane-polarized light). B. Phenocryst of olivine completely altered to iddingsite (moderately olivine-phyric basalt clast) (Sample 330-U1374A-9R-4, 25–29 cm; Thin Section 133; plane-polarized light). C, D. Moderately altered olivine partly replaced by green clay and iron oxyhydroxides (highly plagioclase-olivine-augite-phyric basalt) (Sample 330-U1374A-25R-1, 112–115 cm; Thin Section 161): (C) plane-polarized light, (D) crossed polars. E. Slightly altered phenocrysts of plagioclase with dusty micrograins of carbonates with sieve texture (clasts in sedimentary conglomerate/breccia) (Sample 330-U1374A-22R-4, 49–51 cm; Thin Section 156; crossed polars).

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